Stabilization of burner oils



2,868,628 Patented Jan. 13, 1959 STABILIZATION OF BURNER OILS Joseph A. Chenicek, Bensenville, Ill., assignor to Universal Oil Products Company, Des Plaines, 11]., a corporation of Delaware No Drawing. Application December 5, 1955 Serial No. 550,857

7 Claims. (Cl. 4466) This application is a continuation-in-part of my copending application Serial No. 354,877, filed May 13, 1953, now abandoned, and relates to the stabilization of burner oils and more particularly to a novel method of retarding deterioration of burner oils in storage.

The term burner oil is used in the present application to include hydrocarbon distillates boiling above the range of gasoline and generally boiling within the range of from about 300 F. to about 750 F. These burner oils are marketed under various trade names such as burner oil, fuel oil, furnace oil, diesel oil, etc., and are used principally in burner systems, diesel and combustion engines, and various other industrial and domestic equipment. Also specific-ally included in this classification are jet fuels or other hydrocarbon distillates containing componets boiling above the range of gasoline and also containing lower boiling components. Jet fuels, for example, may have an end boiling point within the range of from about 450 to about 600 F. or higher.

In storage, the burner oil undergoes discoloration and other undesired deterioration. Discoloration of burner oil is objectionable for various reasons, including the customers preference for light colored oils. Other deterioration includes the formation of sediment which is objectionable because the sediment tends to plug strainers,

' burner tips, injectors, etc., and when used as diesel fuel tends to form varnish and sludge in the diesel engine.

Burner oils present a difficult problem because of the wide variations in stability, apparently due to the many difierent sources from which burner oils are obtained. The formation of sediment and discoloration in storge vary considerably with the geographic source of the burner oil and with the treatment that the burner oil has received at the refinery. At present burner oils come principally from non-destructive distillation of pertoleum oil and are commonly referred to in the art as straight run distillate, and from non-catalytic and catalytic cracking process and are commonly referred to in the art as cycle stocks, the latter term being used because the burner oil is separated from a fraction which otherwise is recycled to the cracking process for further conversion therein. Other sources of burner oil may include those produced by the reaction of carbon monoxide with hydrogen, in such processes as the Fischer-Tropsch process, Synthesis process, Oxo process, etc. The stability problems of burner oils become complicated further when the burner oil comprises a blend of two or more different oils. The present invention is directed to a method of retarding deterioration of the burner oil by incorporating therein a particular type of additive.

While the present invention is particularly applicable to the treatment of burner oils and more particularly to the treatment of blends of cycle stocks and straight run distillates, it is understood that the process may be utilized for the stabilization of other hydrocarbon distillates heavier than gasoline including, for example,lubricating oils, transformer oils, turbine oils, etc., which undergo excessive deterioration in storage, but not necessarily with equivalent results.

In one embodiment the present invention relates to a method of retarding deterioration of hydrocarbon distillate heavier than gasoline which comprises adding thereto a small but effective amount of a salt of a dicarboxylic acid having at least 10 carbon atoms and an N-alkyl-l, 3-diaminopropane having an alkyl group of at least 12 carbon atoms.

In a specific embodiment the present invention relates to a method of retarding deterioration of burner oil which comprises incorporating therein from about 0.0001% to about 1% by weight of a salt of a dicarboxylic acid having from about 10 to about 50 carbon atoms and an N-alkyl-1,3-diaminopropane having an alkyl group of from about 12 to about carbon atoms.

In another embodiment the present invention relates to a burner oil tending to discolor in storage containing,

as an additive to retard said discoloration, a minor amount of the novel additive described herein.

The novel additive for use in accordance with the present invention comprises a salt of a dicarboxylic acid having at least 10 carbon atoms and an N-alkyl-1,3- diaminopropane having an alkyl group of at least 12 carbon atoms. The particular dicarboxylic acid and N- alkyl-1,3-diaminopropane to be employed in preparing the additive may vary depending upon the particular oil being stabilized but will be within the range herein set forth. The dicarboxylic acid and N-alkyl-1,3-diaminopropane will be selected so that the salt is readily soluble in the burner oil in the the concentrations of salt to be employed. As a general rule, it is preferred that the total number of carbon atoms in the salt is at least 20 and preferably at least 25. As will hereinafter be set forth in detail, a preferred additive comprises a fatty acid salt of an N-alkyl-1,3-diaminopropane, the last mentioned alkyl group being derived fro-m the fatty acid.

Any suitable N-alkyl-1,3-diaminopropane having an alkyl group of at least 12 carbon atoms may be employed. In general, the number of carbon atoms in the alkyl group will be within the range of from about 12 to abount 20, although the alkyl group may contain a larger number of carbon atoms which generally will not be in excess of about 40 carbon atoms. As hereinbefore set forth, the salt prepared from such an amine contains a sufficient number of carbon atoms so that the additive is readily soluble in the burner oil. Illustrative N-alkyl- 1,3-diaminopropanes meeting the specifications hereinbefore set forth include N-dodecyl-l,3-diaminopropane, N-tridecyl-1,3-diaminopropane, N-tetradecyl-1,3-diaminopropane, N-pentadecyl-l,B-diaminopropane, N-hexadecyl- 1,3-diaminopropane, N-heptadecyl-1,3-diaminopropane, N octadecyl 1,3 diaminopropane, N nonadecyl 1,3- diaminopropane, N-eicosyl-1,3-diaminopropane, N-heneicosyl-1,3-diaminopropane, N-docosyl-l,3-diaminopropane, N tricosyl 1,3 diaminopropane, N tetracosyl 1,3 diaminopropane, N-pentacosyl 1,3 diaminopropane, N- hexacosyl-1,3-diaminopropane, N-heptacosyl-1,3-diaminopropane, N-octacosyl-1,3-diaminopropane, N-nonacosyl- 1,3 diaminopropane, N hentriacontyl 1,3 diamino propane, N-dotriacontyl-1,3-diaminopropane, N-pentatriacontyl-l,3-diaminopropane, etc.

A particularly preferred N-alkyl-1,3-diaminopropane is commercially available under the trade name of Duomeen-T. Other N-alkyl-1,3-diaminopropanes comprise those in which the alkyl group is an alkyl group. derived from lauric acid, coconut oil, soya oil, etc. These Duomeen-T, the alkyl substituent contains from about I 12 to about 20 carbon atoms per group and mostly containing 16 to 18 carbon atoms.

Any suitable dicarboxylic acid may be utilized in forming the salt with the N-alkyl-1,3-diaminopropane. The specific dicarboxylic acid to be employed will be selected with regard to the particular N-alkyl-1,3-diamino-propane employed, so that the resultant salt will be readily soluble in the burner oil and thus the dicarboxylic acid preferably contains at least carbon atoms per molecule. A particularly preferred dicarboxylic acid comprises a mixed by-product acid being marketed commercially under the trade name of VR-l Acid. This acid is a mixture of polybasic acids and has an average molecular weight of about 1000. Another mixed by-product acid is being marketed commercially under the trade name of Dimer Acid. Still another preferred acid is dodecyl succinic acid. Other preferred acids comprise alkyl dicarboxylic acids, the acids having atleast 10 carbon atoms per molecule, and thus may comprise alkyl malonic acid, alkyl succinic acid, alkyl glutaric acid, alkyl adipic acid, alkyl pimelic acid, alkyl suberic acid, alkyl azelaic acid, alkyl sebacic acid, alkyl phthalic acid, and higher molecular weight dicarboxylic acids. It is understood that a mixture of acids may be employed.

In general, the neutral salt of the acid and amine is preferred. The neutral salt is prepared by utilizing stoichiometric amounts of the acid and amine. In other words, the concentration of carboxylic acid and amine is selected so that there is an equivalent number of carboxylic acid groups to amine groups. In other embodiment the salt may be a basic salt, which is prepared by utilizing a deficiency of carboxylic acid groups in relation to the amino group as, for example, by utilizing one equivalent of carboxylic acid per two equivalents of amine. In still another embodiment, an acid salt may be employed, which may be prepared by using an excess of acid with relation to the amine as, for example, two equivalents of acid per one equivalent of amine. It is understood that these different salts are not necessarily equivalent.

The salt may be prepared in any suitable manner and, in general, is readily prepared by admixing the acid and amine at ambient temperature, preferably with vigorous stirring. The salt is readily prepared at room temperature, although slightly elevated temperature which generally will not exceed about 200 F. may be employed when desired. Excessive temperature should not be permitted because of the undesired formation of amides or other reaction products. Depending upon the particular amine and acid employed, it may be desirable to utilize a solvent either in forming a more fluid mixture of the acid and/ or amine before mixing or during the mixing thereof. In some cases it may be desirable to admix the salt with a solvent in order to form a more fluid final product. Any suitable solvent may be used and conveniently may comprise burner oil.

The amount of additive to be employed will depend upon the particular salt and the oil in which it is to be used. In general, the additive will be used in a concentration of less than about 5% by weight and thus may range from about 0.0001% to about 5% by weight and still more preferably within the range of from about 0.0001% to about 1% by weight of burner oil. It is understood that this additive may be used along with the other additives added for specific purposes in burner oil and, when desired, the additive of the present invention may be admixed with the other additive or additives and marketed as a single commodity of multiple purposes.

The following examples are introduced to illustrate further the novelty and utility of the present invention, but not with the intention of unduly limiting the same.

Example I The N-alkyl-l,3-diaminopropane used in this example is Duomeen-T. As hereinbefore set forth, Duomeen- T is available commercially and has a theoretical molecular weight of 320 and a combining molecular weight (based on active ingredient) of about 400. It is a soft paste and has a melting range of from 111 to 118 F. The acid used in this example is VR-l Acid which, as hereinbefore set forth, is available commercially and is liquid at 77 F., has an acid number of about 150 and an iodine number of about 36. It is believed that this acid contains about 35 carbon atoms per molecule. As heretofore mentioned, this acid is a byproduct and, therefore, is available at relatively low cost. Because it produces a very effective additive, as will be shown in the following examples, the use of this acid is particularly attractive because of its low cost. 374 parts by weight of Duo-meen-T are warmed moderately (at a temperature of about 125 F.) and 726 parts of VR1 Acid are commingled therewith. The mixing is effected at room temperature and the mixture is vigorously stirred. A hydrocarbon solvent is added to increase fluidity.

The resultant salt is a neutral salt and was utilized for the stabilization of commercial burner oils. The burner oil samples were subjected to accelerated aging at 212 F. for 20 hours and the colors of the different samples were determined in a Lumitron, Model 402E, Spectrophotometer. Distilled water is rated as and a very dark oil is rated as 0 in this analysis.

A commercial No. 2 catalytic burner oil had an original color of 93.7. After accelerated aging, the color of the oil dropped to three. 0.005% by weight of the salt prepared in the manner hereinbefore set forth was added to another sample of this burner oil and, after accelerated aging, the sample had a color of 71.

It will be noted that, after the accelerated aging, the sample without additive became very dark, having a color of three, whereas the sample with additive still had a color of 71 after the accelerated aging.

Example 11 As hereinbefore set forth, one of the important objectives is that the burner oil will not clog the equipment in which it is used. This is determined in an accelerated recycle test in which a two gallon sample of the oil is recycled by a gear pump at a constant rate of flow, first through a nozzle of the gun burner type having the usual screen filter and then through an edge filter having 0.002 openings. Plugging of the filter on the nozzle is indicated by an increase in pressure on the pump discharge, while plugging of the edge filter is indicated by the development of suction on the pump intake side. The suction on the pump intake continues at 0 for an interval and then shows a rapid increase, thereby simulating an induction period. The time necessary for this increase is designated as inflection point. This test is fairly reproducible, and indicates the plugging characteristics of the oil.

The oil used in this example was acommercial No. 2 fuel oil. This oil had an original inflection point of 33 hours. Upon the addition of 0.005% by weight of the additive described in Example I, the inflection point was increased to 61. Upon the addition of 0.01% by weight of this additive to another sample of the oil, the inflection point was increased to 84 hours.

From the above data it will be shown that the additive of the present invention served to considerably prolong the inflection point of the oil and thereby to retard its plugging characteristics.

Example III The oil used in this example was a West Texas thermal .No. 2 burner oil which had an original inflection point of seven hours. Upon the addition of 0.005% by weight of the additive-described in Example I, the inflection point of the oil was increased to 14 hours, thus doubling the time before plugging occurred.

Example IV The additive used in this example was a basic salt of Duomeen-T and VR-l Acid and was prepared by admixing two equivalents of amine per one of acid. 0.01% by weight of the additive increased the inflection point of another sample of the No. 2 fuel oil described in Example I from 33 hours to 84 hours.

Example V The additive used in this example is a neutral salt of dodecyl succinic acid and Duomeen-T.

0.005% by weight of this additive increases the inflection point of another sample of another fuel oil described in Example I.

Example VI Example VII A jet fuel comprising a mixture of cracked cycle stock and straight run distillate is stabilized against discoloration by the addition thereto of 0.01% by weight of the salt prepared as described in Example VII.

Example VIII Lubricating oil is stabilized against discoloration by incorporating therein 0.5% by weight of the additive prepared in the manner described in Example I.

I claim as my invention:

1. A hydrocarbon distillate heavier than gasoline normally tending to undergo discoloration in storage containing, as an inhibitor against said discoloration, from about 0.0001% to about 5% by weight of a salt of a dicarboxylic acid having at least 10 carbon atoms and an N-alkyl-1,3-diaminopropane having an alkyl group of at least 12 carbon atoms.

2. A hydrocarbon distillate heavier than gasoline normally tending to undergo discoloration in storage containing, as an inhibitor against said discoloration, from about 0.0001% to about 5% by weight of a salt of a dicarboxylic acid having from about 10 to about 50 carbon atoms per molecule and an N-alkyl-1,3-diaminopropane having an alkyl group of from about 12 to about carbon atoms.

3. The composition as defined in claim 2 further characterized in that said alkyl group is derived from tallow.

4. The composition as defined in claim 2 further characterized in that said alkyl group is derived from lauric acid.

5. The composition as defined in claim 2 further characterized in that said alkyl group is derived from coconut oil.

6. The composition as defined in claim 2 further characterized in that said alkyl group is derived from soyaoil.

7. A hydrocarbon oil boiling in the range of from about 300 F. to about 750 F. and containing from about 0.0001% to about 5% by weight of a salt of a dicarboxylic acid having at least 10 carbon atoms and an N-alkyl-1,3-diaminopropane having an alkyl group of at least 12 carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS 2,329,251 Chenicek Sept. 14, 1943 2,369,490 Proell Feb. 13, 1945 2,736,658 Pfohl et a1 Feb. 28, 1956 

1. A HYDROCARBON DISTILLATE HEAVIER THAN GASOLINE NORMALLY TENDING TO UNDERGO DISCOLORATION IN STORAGE CONTAINING, AS AN INHIBITOR AGAINST SAID DISCOLORATION, FROM ABOUT 0.0001% TO ABOUT 5% BY WEIGHT OF A SALT OF A DICARBOXYLIC ACID HAVING AT LEAST 10 CARBON ATOMS AND AN N-ALKYL-1,3-DIAMINOPROPANE HAVING AN ALKYL GROUP OF AT LEAST 12 CARBON ATOMS. 